Numerous recommendation systems have been built over the years and tagging has become a popular phenomenon on the Web. In Web 2.0 systems like Flickr and even in older Web 1.0 sites, a large number of tagging systems such as digg, del.ici.ous, etc. have been created to let users indicate their approval of a Web page. As a result of a large number of users tagging a site, its value is potentially enhanced. Highly rated sites get featured in the front page of digg, which allows other users to follow popular pages. Search engines have been using popularity-based rankings (e.g., PageRank) for years to rank order the search results.
When a very large number of users approve of a site, it will likely be of interest to many other users. However sites that are rated favorably by a smaller number of users may also be of interest. It is often unclear and difficult to discern the importance or value of a site which has few ratings, though even these few ratings may be more valuable than ratings of a site which has garnered many more ratings. Other such examples occur in the offline world. For example, a recommendation by a dozen friends of a restaurant may be more helpful to a person than a global popularity rating obtained through a ranking system such as Zagat. When a user examines a particular piece of content such as a Web page, a search result, or a particular cultural event, the user often relies on external editors to evaluate the content. However, a user's friends are more familiar with the user's tastes and for that reason their recommendations are much more valuable to a user than recommendations from even large numbers of people who don't know the user.
Currently, available online systems, such as those described above, allow anyone to tag a site. The followers of the tags do not have any information beyond quantity. There has been a long-felt and unsolved need to improve upon ratings to the user viewing the ratings.